Trading & Investing Simulation Platform

Build a paper trading simulation platform called "Paper" — a realistic, risk-free environment for learning to trade and invest. Core features: - Portfolio setup: user starts with $100,000 in virtual cash. Real-time stock and ETF prices via Yahoo Finance or Alpha Vantage API - Trade execution: market and limit orders supported. Simulate 0.1% slippage on market orders. Commission of $1 per trade (realistic friction without being punitive) - Performance dashboard: P&L chart (daily), total return, ...